The world's worst known nuclear disaster was at Chernobyl, in the Ukraine. The Chernobyl Disaster, as it is called, happened on April 26, 1986. There is a link to a Wikipedia article on this below.
Because of the disaster at the nuclear power plant in Chernobyl, not many people live there. Chernobyl, Ukraine has a population of 500.
You probably mean at Chernobyl in the Ukraine, in 1986
the nuclear meltdown at Chernobyl.
The Ukraine
Chernobyl, Ukraine, in 1986, is probably what you are thinking of.
The disaster occurred at the Chernobyl Nuclear Power Plant in Ukraine on April 26, 1986.
Nuclear power accidents are a disaster. The 1986 nuclear accident at the Chernobyl Nuclear Power Plant in Ukraine was a catastrophic accident.
There was no famous disaster (or anything else) at Chernobyl in Russia as there is no such place. However for the disaster that occurred in Chernobyl in the Ukraine, please see the related question.
Chernobyl is a city in Ukraine. It was the site of a nuclear disaster in the 1980's and has since been totally abandoned. It is also featured on the Call of Duty game, Modern Warfare as the backdrop to a playable level.
Chernobyl, Ukraine, 1986
Ukraine